Are penguins black-and-white?

Contribution of low-energy ''eye'' and ''figure-eight'' quark diagrams to the K → π weak transitions are studied in a hadron-level phenomenological approach. It is shown that these contributions may be estimated by considering meson-cloud effect. If all intermediate mesons under consideration are degenerate only the ''eye'' (low-energy penguin) diagrams is nonvanishing. When allowance is made for smaller mass of pseudoscalar mesons, the contribution of ''figure-eight'' diagrams turns out to enhance the ΔI = 1/2 (suppress the ΔI = 3/2) amplitudes naturally. The overall long-distance-induced enhancement of the ratio of the Δ I = 1/2 amplitudes over the Δ I = 3/2 amplitudes is estimated at around 4-8. (author). 27 refs, 3 figs, 2 tabs